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/* Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.activiti.bpmn;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.List;
import java.util.Map;
import java.util.UUID;

import javax.swing.SwingConstants;

import org.activiti.bpmn.model.BoundaryEvent;
import org.activiti.bpmn.model.BpmnModel;
import org.activiti.bpmn.model.CallActivity;
import org.activiti.bpmn.model.DataObject;
import org.activiti.bpmn.model.Event;
import org.activiti.bpmn.model.FlowElement;
import org.activiti.bpmn.model.FlowElementsContainer;
import org.activiti.bpmn.model.Gateway;
import org.activiti.bpmn.model.GraphicInfo;
import org.activiti.bpmn.model.Process;
import org.activiti.bpmn.model.SequenceFlow;
import org.activiti.bpmn.model.SubProcess;
import org.activiti.bpmn.model.Task;

import com.mxgraph.layout.hierarchical.mxHierarchicalLayout;
import com.mxgraph.model.mxCell;
import com.mxgraph.model.mxGeometry;
import com.mxgraph.util.mxConstants;
import com.mxgraph.util.mxPoint;
import com.mxgraph.view.mxCellState;
import com.mxgraph.view.mxEdgeStyle;
import com.mxgraph.view.mxGraph;

/**
 * Auto layouts a {@link BpmnModel}.
 * 
 * @author Joram Barrez
 */
public class BpmnAutoLayout {
  
  private static final String STYLE_EVENT = "styleEvent";
  private static final String STYLE_GATEWAY = "styleGateway";
  private static final String STYLE_SEQUENCEFLOW = "styleSequenceFlow";
  private static final String STYLE_BOUNDARY_SEQUENCEFLOW = "styleBoundarySequenceFlow";
  
  protected BpmnModel bpmnModel;
  
  protected int eventSize = 30;
  protected int gatewaySize = 40;
  protected int taskWidth = 100;
  protected int taskHeight = 60;
  protected int subProcessMargin = 20;
  
  protected mxGraph graph;
  protected Object cellParent;
  protected Map sequenceFlows;
  protected List boundaryEvents;
  protected Map handledFlowElements;
  protected Map generatedVertices;
  protected Map generatedEdges;
  
  public BpmnAutoLayout(BpmnModel bpmnModel) {
    this.bpmnModel = bpmnModel;
  }
  
  public void execute() {
    // Reset any previous DI information
    bpmnModel.getLocationMap().clear();
    bpmnModel.getFlowLocationMap().clear();
    
    // Generate DI for each process
    for (Process process : bpmnModel.getProcesses()) {
      layout(process);
      
      // Operations that can only be done after all elements have received DI
      translateNestedSubprocesses(process);
    }
  }

  protected void layout(FlowElementsContainer flowElementsContainer) {
    graph = new mxGraph();
    cellParent = graph.getDefaultParent();
    graph.getModel().beginUpdate();
    
    handledFlowElements = new HashMap();
    generatedVertices = new HashMap();
    generatedEdges = new HashMap();
    
    sequenceFlows = new HashMap(); // Sequence flow are gathered and processed afterwards, because we must be sure we alreadt found source and target
    boundaryEvents = new ArrayList(); // Boundary events are gathered and processed afterwards, because we must be sure we have its parent
    
    
    // Process all elements
    for (FlowElement flowElement : flowElementsContainer.getFlowElements()) {
    	
      if (flowElement instanceof SequenceFlow) {
        handleSequenceFlow((SequenceFlow) flowElement);
      } else if (flowElement instanceof Event) {
        handleEvent(flowElement);
      } else if (flowElement instanceof Gateway) {
        createGatewayVertex(flowElement);
      } else if (flowElement instanceof Task || flowElement instanceof CallActivity) {
        handleActivity(flowElement);
      } else if (flowElement instanceof SubProcess) {
        handleSubProcess(flowElement);
      }
      
      handledFlowElements.put(flowElement.getId(), flowElement);
    }
    
    // Process gathered elements
    handleBoundaryEvents();
    handleSequenceFlow();
    
    // All elements are now put in the graph. Let's layout them!
    CustomLayout layout = new CustomLayout(graph, SwingConstants.WEST);
    layout.setIntraCellSpacing(100.0);
    layout.setResizeParent(true);
    layout.setFineTuning(true);
    layout.setParentBorder(20);
    layout.setMoveParent(true);
    layout.setDisableEdgeStyle(false);
    layout.setUseBoundingBox(true);
    layout.execute(graph.getDefaultParent());
    
    graph.getModel().endUpdate();
    
    generateDiagramInterchangeElements();
  }

  // BPMN element handling
  
  protected void ensureSequenceFlowIdSet(SequenceFlow sequenceFlow) {
    // We really must have ids for sequence flow to be able to generate stuff
    if (sequenceFlow.getId() == null) {
      sequenceFlow.setId("sequenceFlow-" + UUID.randomUUID().toString());
    }
  }

  protected void handleSequenceFlow(SequenceFlow sequenceFlow) {
    ensureSequenceFlowIdSet(sequenceFlow);
    sequenceFlows.put(sequenceFlow.getId(), sequenceFlow);
  }
  
  protected void handleEvent(FlowElement flowElement) {
    // Boundary events are an exception to the general way of drawing an event
    if (flowElement instanceof BoundaryEvent) {
      boundaryEvents.add((BoundaryEvent) flowElement);
    } else {
      createEventVertex(flowElement);
    }
  }
  
  protected void handleActivity(FlowElement flowElement) {
    Object activityVertex = graph.insertVertex(cellParent, flowElement.getId(), "", 0, 0, taskWidth, taskHeight);
    generatedVertices.put(flowElement.getId(), activityVertex);
  }
  
  protected void handleSubProcess(FlowElement flowElement) {
    BpmnAutoLayout bpmnAutoLayout = new BpmnAutoLayout(bpmnModel);
    bpmnAutoLayout.layout((SubProcess) flowElement);
    
    double subProcessWidth = bpmnAutoLayout.getGraph().getView().getGraphBounds().getWidth();
    double subProcessHeight = bpmnAutoLayout.getGraph().getView().getGraphBounds().getHeight();
    Object subProcessVertex = graph.insertVertex(cellParent, flowElement.getId(), "", 0, 0, 
            subProcessWidth + 2 * subProcessMargin, subProcessHeight + 2 * subProcessMargin);
    generatedVertices.put(flowElement.getId(), subProcessVertex);
  }
  
  protected void handleBoundaryEvents() {
    for (BoundaryEvent boundaryEvent : boundaryEvents) {
      mxGeometry geometry = new mxGeometry(0.8, 1.0, eventSize, eventSize);
      geometry.setOffset(new mxPoint(-(eventSize/2), -(eventSize/2)));
      geometry.setRelative(true);
      mxCell boundaryPort = new mxCell(null, geometry, "shape=ellipse;perimter=ellipsePerimeter");
      boundaryPort.setId("boundary-event-" + boundaryEvent.getId());
      boundaryPort.setVertex(true);

      Object portParent = null;
      if (boundaryEvent.getAttachedToRefId() != null) {
        portParent = generatedVertices.get(boundaryEvent.getAttachedToRefId());
      } else if (boundaryEvent.getAttachedToRef() != null) {
        portParent = generatedVertices.get(boundaryEvent.getAttachedToRef().getId());
      } else {
        throw new RuntimeException("Could not generate DI: boundaryEvent '" + boundaryEvent.getId() + "' has no attachedToRef");
      }
      
      graph.addCell(boundaryPort, portParent);
      generatedVertices.put(boundaryEvent.getId(), boundaryPort);
    }
  }
  
  protected void handleSequenceFlow() {
    
    Hashtable edgeStyle = new Hashtable();
    edgeStyle.put(mxConstants.STYLE_ORTHOGONAL, true);
    edgeStyle.put(mxConstants.STYLE_EDGE, mxEdgeStyle.ElbowConnector);
    edgeStyle.put(mxConstants.STYLE_ENTRY_X, 0.0);
    edgeStyle.put(mxConstants.STYLE_ENTRY_Y, 0.5);
    graph.getStylesheet().putCellStyle(STYLE_SEQUENCEFLOW, edgeStyle);
    
    Hashtable boundaryEdgeStyle = new Hashtable();
    boundaryEdgeStyle.put(mxConstants.STYLE_EXIT_X, 0.5);
    boundaryEdgeStyle.put(mxConstants.STYLE_EXIT_Y, 1.0);
    boundaryEdgeStyle.put(mxConstants.STYLE_ENTRY_X, 0.5);
    boundaryEdgeStyle.put(mxConstants.STYLE_ENTRY_Y, 1.0);
    boundaryEdgeStyle.put(mxConstants.STYLE_EDGE, mxEdgeStyle.orthConnector);
    graph.getStylesheet().putCellStyle(STYLE_BOUNDARY_SEQUENCEFLOW, boundaryEdgeStyle);
    
    for (SequenceFlow sequenceFlow : sequenceFlows.values()) {
      Object sourceVertex = generatedVertices.get(sequenceFlow.getSourceRef());
      Object targertVertex = generatedVertices.get(sequenceFlow.getTargetRef());
      
      String style = null;
     
      if (handledFlowElements.get(sequenceFlow.getSourceRef()) instanceof BoundaryEvent) {
        // Sequence flow out of boundary events are handled in a different way,
        // to make them visually appealing for the eye of the dear end user.
        style = STYLE_BOUNDARY_SEQUENCEFLOW;
      } else {
        style = STYLE_SEQUENCEFLOW;
      }
      
      Object sequenceFlowEdge = graph.insertEdge(cellParent, sequenceFlow.getId(), "", sourceVertex, targertVertex, style);
      generatedEdges.put(sequenceFlow.getId(), sequenceFlowEdge);
    }
  }
  
  // Graph cell creation
  
  protected void createEventVertex(FlowElement flowElement) {
    // Add styling for events if needed
    if (!graph.getStylesheet().getStyles().containsKey(STYLE_EVENT)) {
      Hashtable eventStyle = new Hashtable();
      eventStyle.put(mxConstants.STYLE_SHAPE, mxConstants.SHAPE_ELLIPSE);
      graph.getStylesheet().putCellStyle(STYLE_EVENT, eventStyle);  
    }
    
    // Add vertex representing event to graph
    Object eventVertex = graph.insertVertex(cellParent, flowElement.getId(), "", 0, 0, eventSize, eventSize, STYLE_EVENT);
    generatedVertices.put(flowElement.getId(), eventVertex);
  }
  
  protected void createGatewayVertex(FlowElement flowElement) {
    // Add styling for gateways if needed
    if (graph.getStylesheet().getStyles().containsKey(STYLE_GATEWAY)) {
      Hashtable style = new Hashtable();
      style.put(mxConstants.STYLE_SHAPE, mxConstants.SHAPE_RHOMBUS);
      graph.getStylesheet().putCellStyle(STYLE_GATEWAY, style);
    }
    
    // Create gateway node 
    Object gatewayVertex = graph.insertVertex(cellParent, flowElement.getId(), "", 0, 0, gatewaySize, gatewaySize, STYLE_GATEWAY);
    generatedVertices.put(flowElement.getId(), gatewayVertex);
  }
  
  // Diagram interchange generation
  
  protected void generateDiagramInterchangeElements() {
    generateActivityDiagramInterchangeElements();
    generateSequenceFlowDiagramInterchangeElements();
  }
  
  protected void generateActivityDiagramInterchangeElements() {
    for (String flowElementId : generatedVertices.keySet()) {
      Object vertex = generatedVertices.get(flowElementId);
      mxCellState cellState = graph.getView().getState(vertex);
      GraphicInfo subProcessGraphicInfo = createDiagramInterchangeInformation(handledFlowElements.get(flowElementId), 
              (int) cellState.getX(), (int) cellState.getY(), (int) cellState.getWidth(), (int) cellState.getHeight());
      
      // The DI for the elements of a subprocess are generated without knowledge of the rest of the graph
      // So we must translate all it's elements with the x and y of the subprocess itself
      if (handledFlowElements.get(flowElementId) instanceof SubProcess) {

      	// Always expanded when auto layouting
        subProcessGraphicInfo.setExpanded(true);
      }
    }
  }

  protected void generateSequenceFlowDiagramInterchangeElements() {
    for (String sequenceFlowId : generatedEdges.keySet()) {
      Object edge = generatedEdges.get(sequenceFlowId);
      List points = graph.getView().getState(edge).getAbsolutePoints();
      
      // JGraphX has this funny way of generating the outgoing sequence flow of a gateway
      // Visually, we'd like them to originate from one of the corners of the rhombus,
      // hence we force the starting point of the sequence flow to the closest rhombus corner point.
      FlowElement sourceElement = handledFlowElements.get(sequenceFlows.get(sequenceFlowId).getSourceRef()); 
      if (sourceElement instanceof Gateway && ((Gateway) sourceElement).getOutgoingFlows().size() > 1) {
        mxPoint startPoint = points.get(0);
        Object gatewayVertex = generatedVertices.get(sourceElement.getId());
        mxCellState gatewayState = graph.getView().getState(gatewayVertex);
        
        mxPoint northPoint = new mxPoint(gatewayState.getX() + (gatewayState.getWidth()) / 2, gatewayState.getY());
        mxPoint southPoint = new mxPoint(gatewayState.getX() + (gatewayState.getWidth()) / 2, gatewayState.getY() + gatewayState.getHeight());
        mxPoint eastPoint = new mxPoint(gatewayState.getX() + gatewayState.getWidth(), gatewayState.getY() + (gatewayState.getHeight()) / 2);
        mxPoint westPoint = new mxPoint(gatewayState.getX(), gatewayState.getY() + (gatewayState.getHeight()) / 2);
        
        double closestDistance = Double.MAX_VALUE;
        mxPoint closestPoint = null;
        for (mxPoint rhombusPoint : Arrays.asList(northPoint, southPoint, eastPoint, westPoint)) {
          double distance = euclidianDistance(startPoint, rhombusPoint);
          if (distance < closestDistance) {
            closestDistance = distance;
            closestPoint = rhombusPoint;
          }
        }
        startPoint.setX(closestPoint.getX());
        startPoint.setY(closestPoint.getY());
        
        // We also need to move the second point.
        // Since we know the layout is from left to right, this is not a problem
        if (points.size() > 1) {
          mxPoint nextPoint = points.get(1);
          nextPoint.setY(closestPoint.getY());
        }
        
      }
      
      createDiagramInterchangeInformation((SequenceFlow) handledFlowElements.get(sequenceFlowId), optimizeEdgePoints(points));
    }
  }

  protected double euclidianDistance(mxPoint point1, mxPoint point2) {
    return Math.sqrt( ( (point2.getX() - point1.getX())*(point2.getX() - point1.getX()) 
            + (point2.getY() - point1.getY())*(point2.getY() - point1.getY()) ) );
  }
  
  // JGraphX sometime generates points that visually are not really necessary.
  // This method will remove any such points.
  protected List optimizeEdgePoints(List unoptimizedPointsList) {
    List optimizedPointsList = new ArrayList();
    for (int i=0; i 0 && i != unoptimizedPointsList.size() - 1) {
        
        mxPoint previousPoint = unoptimizedPointsList.get(i - 1);
        mxPoint nextPoint = unoptimizedPointsList.get(i + 1);
        
        if (currentPoint.getX() >= previousPoint.getX() 
                && currentPoint.getX() <= nextPoint.getX()
                && currentPoint.getY() == previousPoint.getY()
                && currentPoint.getY() == nextPoint.getY()) {
          keepPoint = false;
        } else if (currentPoint.getY() >= previousPoint.getY()
                && currentPoint.getY() <= nextPoint.getY()
                && currentPoint.getX() == previousPoint.getX()
                && currentPoint.getX() == nextPoint.getX()) {
          keepPoint = false;
        }
        
      }
      
      if (keepPoint) {
        optimizedPointsList.add(currentPoint);
      }
      
    }
    
    return optimizedPointsList;
  }
  
  protected GraphicInfo createDiagramInterchangeInformation(FlowElement flowElement, int x, int y, int width, int height) {
    GraphicInfo graphicInfo = new GraphicInfo();
    graphicInfo.setX(x);
    graphicInfo.setY(y);
    graphicInfo.setWidth(width);
    graphicInfo.setHeight(height);
    graphicInfo.setElement(flowElement);
    bpmnModel.addGraphicInfo(flowElement.getId(), graphicInfo);
    
    return graphicInfo;
  }
  
  protected void createDiagramInterchangeInformation(SequenceFlow sequenceFlow, List waypoints) {
    List graphicInfoForWaypoints = new ArrayList();
    for (mxPoint waypoint : waypoints) {
      GraphicInfo graphicInfo = new GraphicInfo();
      graphicInfo.setElement(sequenceFlow);
      graphicInfo.setX(waypoint.getX());
      graphicInfo.setY(waypoint.getY());
      graphicInfoForWaypoints.add(graphicInfo);
    }
    bpmnModel.addFlowGraphicInfoList(sequenceFlow.getId(), graphicInfoForWaypoints);
  }
  
  /**
   * Since subprocesses are autolayouted independently (see {@link #handleSubProcess(FlowElement)}),
   * the elements have x and y coordinates relative to the bounds of the subprocess (thinking the subprocess 
   * is on (0,0). This however, does not work for nested subprocesses, as they need to 
   * take in account the x and y coordinates for each of the parent subproceses.
   * 
   * This method is to be called after fully layouting one process,
   * since ALL elements need to have x and y.
   */
  protected void translateNestedSubprocesses(Process process) {
  	for (SubProcess nestedSubProcess : process.findFlowElementsOfType(SubProcess.class, false)) {
  		translateNestedSubprocessElements(nestedSubProcess);
  	}
  }
  
  protected void translateNestedSubprocessElements(SubProcess subProcess) {
  	
  	GraphicInfo subProcessGraphicInfo = bpmnModel.getLocationMap().get(subProcess.getId());
  	double subProcessX = subProcessGraphicInfo.getX();
  	double subProcessY = subProcessGraphicInfo.getY();
  	
  	List nestedSubProcesses = new ArrayList();
  	for (FlowElement flowElement : subProcess.getFlowElements()) { 
  		
  		if (flowElement instanceof SequenceFlow) {
				List graphicInfos = bpmnModel.getFlowLocationMap().get(flowElement.getId());
				for (GraphicInfo graphicInfo : graphicInfos) {
					graphicInfo.setX(graphicInfo.getX() + subProcessX + subProcessMargin);
					graphicInfo.setY(graphicInfo.getY() + subProcessY + subProcessMargin);
				} 
			} else if (flowElement instanceof DataObject == false) {
				
				// Regular element
				GraphicInfo graphicInfo = bpmnModel.getLocationMap().get(flowElement.getId());
				graphicInfo.setX(graphicInfo.getX() + subProcessX + subProcessMargin);
				graphicInfo.setY(graphicInfo.getY() + subProcessY + subProcessMargin);
			}
  		
  		if (flowElement instanceof SubProcess) {
  			nestedSubProcesses.add((SubProcess) flowElement);
  		}
  		
  	}
  	
  	// Continue for next level of nested subprocesses
   	for (SubProcess nestedSubProcess : nestedSubProcesses) {
  		translateNestedSubprocessElements(nestedSubProcess);
  	}
  }
  
  // Getters and Setters
  
  
  public mxGraph getGraph() {
    return graph;
  }

  public void setGraph(mxGraph graph) {
    this.graph = graph;
  }
  
  public int getEventSize() {
    return eventSize;
  }

  public void setEventSize(int eventSize) {
    this.eventSize = eventSize;
  }
  
  public int getGatewaySize() {
    return gatewaySize;
  }
  
  public void setGatewaySize(int gatewaySize) {
    this.gatewaySize = gatewaySize;
  }
  
  public int getTaskWidth() {
    return taskWidth;
  }

  public void setTaskWidth(int taskWidth) {
    this.taskWidth = taskWidth;
  }

  public int getTaskHeight() {
    return taskHeight;
  }
  
  public void setTaskHeight(int taskHeight) {
    this.taskHeight = taskHeight;
  } 
  
  public int getSubProcessMargin() {
    return subProcessMargin;
  }
  
  public void setSubProcessMargin(int subProcessMargin) {
    this.subProcessMargin = subProcessMargin;
  }

  // Due to a bug (see http://forum.jgraph.com/questions/5952/mxhierarchicallayout-not-correct-when-using-child-vertex)
  // We must extend the default hierarchical layout to tweak it a bit (see url link) otherwise the layouting crashes.
  //
  // Verify again with a later release if fixed (ie the mxHierarchicalLayout can be used directly)
  static class CustomLayout extends mxHierarchicalLayout {
    
    public CustomLayout(mxGraph graph, int orientation) {
      super(graph, orientation);
      this.traverseAncestors = false;
    }
    
  }
  
}




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